The present invention relates to an apparatus and the like for embedding information into data without making a change to the contents of the data.
The quality of digital data (data) recorded to a tape medium, such as a magnetic tape, will not degrade even if the data is copied to other tape medium. However, even now, it is difficult to distinguish whether a tape medium on which data is recorded is an original one or a copied one. This is because the recorded data can be copied sequentially using another tape drive, in a general method of recording data to a tape medium, the method specifying data is arranged and recorded sequentially along the driving direction of the tape medium, and thus. In other words, in a case where data is recorded sequentially and in regular order, simply copying this to other tape medium allows a copy of the original tape medium to be created easily.
Under these circumstances, a technique for enabling a user to discriminate whether a tape medium to which data is recorded is an original or a copy has been awaited. Here, among the data recorded to a tape medium, there are many data whose contents are not allowed to be changed. Accordingly, a technique has been proposed in which information for discriminating whether a tape medium is an original or a copy is embedded without making a change to the contents of the data (e.g., refer to Japanese Patent Application Publication No. 2004-145920). Specifically, in Patent Document 1, when data is divided into a plurality of data sets and the data sets are recorded to a tape medium, a distance between a data set and the subsequent data set is adjusted in order to embed information into the data.
However, in the technique of embedding information using a distance between the data sets as in the case of Patent Document 1, there is room for further increase in efficiency by improving the following point.
Specifically, the point is that a quantitative increase in the information to be embedded directly leads to waste of recording area.